Fix error message for deleteRule()

Previous to this CL, deleteRule on an empty style sheet would throw a
confusingly-worded IndexSizeError. Now, it properly throws a RangeError.

For example:

const styleEl = document.createElement('style');
document.head.appendChild(styleEl);
styleEl.sheet.deleteRule(0);
--> Uncaught RangeError: Failed to execute 'deleteRule' on 'CSSStyleSheet': The index provided (0) is outside the range [0, 0).

Bug: 949523
Change-Id: I306409f53be88f4bead261dd171466fd3aad5565
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1561410
Auto-Submit: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650697}
2 files changed